Optimal timeframe for achieving biochemical remission in Crohn's disease patients treated with first-line biologics: A retrospective multicenter study

Predicting treatment response in Crohn's disease (CD) patients initiating biological therapy is crucial. The first step involves considering symptom control and normalization of C-reactive protein (CRP). However, data on the actual rates of achieving CRP normalization and the appropriate timeframe are lacking. Therefore, we aim to investigate the rate of attaining CRP normalization and identify its optimal timeframe in CD patients initiating biological therapy. In this retrospective multi-center study, we analyzed moderate to severe CD patients initiating biological therapy from January 2012 to July 2023. The primary outcome was the rate and timeframe for achieving CRP normalization. Secondary outcomes included clinical outcomes in patients who achieved CRP normalization and factors associated with early CRP normalization. Of 183 patients, 123 (67.2%) achieved CRP normalization, with a median duration of 3.8 months (interquartile range 1.4 to 7.4 months). The duration and value difference for CRP normalization between anti-tumor necrosis factor agents, ustekinumab, and vedolizumab were statistically insignificant. Cumulative rates of CD-related hospitalization, intestinal resection, and drug discontinuation over 8 years were 11.4%, 2.4%, and 12.2%, respectively. The duration of CRP normalization correlates with drug discontinuation (area under the curve: 0.64). Treatment with 5-aminosalicylic acid (HR 2.77; 95% confidence interval [CI] 1.26-6.11) and high albumin level (HR 1.64, 95% CI 1.04-2.61) favored early CRP normalization, whereas structuring behavior less likely than inflammatory behavior (HR 0.43, 95% CI 0.19-0.96). We have provided the actual rate of achieving CRP normalization and its appropriate timeframe as an initial target in CD treatment.